Fuzzy white things

[CWalters]

Any idea what these are attatched to the bottom of my frag plug

 

[JaimeAdams]

Pineapple Sponge. Harmless

 

[hoffmeyerz]

 

[Cthulukelele]

They're honestly nice to have around. Hearty and filter nutrients out of the water. I Def wouldn't remove them. They can grow like mad if your nutrients are high though--mainly in the darker areas like your sump.